Different Browser Windows

When having a Browser Window opened, not connected to VPN and I’ll open a second window (not a tab…) an do connect on that window to VPN (obv. via the VPN Browser Extension), all other window do connect to that VPN. Is this works-as-designed or a bug?

So if I wanted to have a window not connected to VPN and the other one connected to VPN, I’ll have to use different browsers?

This is expected. Because if it was scoped to window and the users don’t realize it, they might connect, think they are connected everywhere and then actually browse unprotected when switching to another window.
However on Chromium-browsers the profile feature can be used. It allows to have another window with isolated session and so to have them on different servers and states.
Firefox has profiles too (https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles#w_starting-the-profile-manager) Maybe they can achieve the same result.

I’d say it’s by design ! If you use the same browser, and enable VPN only on a specific tab, nothing prevents an attacker to use an “unprotected tab” to gain access to content being viewed in the VPN tab.
Maybe using containers tab could prevent that but I don’t think they implement the VPN extension to work with that

So yes if you want no VPN + VPN depending on the usage you’ll have to use différents browsers but I would not recommended that either.

Enabling VPN in a tab doesn’t prevent anyone to see the clear DNS request for example, so not that good in terms of privacy.

If you want to be protected at the best on windows, I think enabling it for the whole system would be a better option.

If you still want to have multiple internet usage at once and still be secured, try to look at virtual machines for tunneled connections and use your usual browser for day-to-day browsing without a VPN

Proton has a browser extension now?

I must check this out.

So if I wanted to have a window not connected to VPN and the other one connected to VPN, I’ll have to use different browsers?

Yes, you have to.